"I do not have rice for sushi."
Translation:У меня нет риса для суши.
You probably remembered the use of на in на завтрак / на обед / на ужин / на десерт. This is mostly used with these meals. It does not fit here.
- there is another, fairly narrow meaning of на that sort of corresponds to English "for". It means a quantity of resource to be depleted in making/buying/achieving something—e.g., "money for (hiring) another employee" , "concrete enough for 2 floors".
«Нет» is used in the following cases:
- When answering a yes/no question: «Вы говори́те по-узбе́кски?» — «Нет». ('Do you speak Uzbek?' 'No, I don't.')
- When talking about absence of something, we use «нет» + Genitive case form of the thing missing. This is usually translated 'there's no' or 'there're no': «Во всём до́ме нет све́та» ('There's no electricity in the whole house.' Literally: in whole house there-is-no light). In this construction «нет» may be replaced with «не́ту» in colloquial speech: «Во всём го́роде нету магазина комиксов» (There's not [a single] comics shop in the whole town. Literally: In whole town there-is-no shop of-comics)
- As a particular case of the previous construction, when a preposition «у» is used to indicate possession, we translate it with «don't have», «have no»: «У меня́ нет соба́ки» (I don't have a dog. Literally: at me there-is-no dog)
In all the other cases, we use «не». Notably:
- When negating most verbs: «Я не зна́ю» (I don't know)
- When negating adjectives (it's spelled as one word then): «несве́жий хлеб» (non-fresh bread, i.e. stale bread)
- In sentences of the type «X is not Y»: «Я не ве́дьма» 'I'm not [a] witch'.
There is one more use, a short negation of a statement with the omission of the "real" verb or other predicate that would carry the meaning:
- Мы инженеры, а они нет. = We are engineers, and they aren't.
- Мария спит, а я нет. = Maria is asleep (sleeping) and I am not.
- Анна любит Тома, а он её нет. = Anna loves Tom, yet he does not love her.
Yes, all loanwords that end in -и, -у, -э, or -ю in the Nominative singular form will be indeclinable (e.g., каратэ, Луи, жюри, табу, алоэ, каноэ, меню). If you check the Russian declension patterns, you will see these vowels are just not supported as a base form ending.
Borrowed nouns ending in -о/-е/-ё are indeclinable, too, even though they could have been assigned the same pattern as яйцо "egg", море "sea". Curiously, эхо is declinable but I cannot think of any other exception.
Человек человеку волк, а пони пони пони.
За + Accusative corresponds to English "for" in the following cases:
- support ("He is for Liberal Democrats", "Are you for or against me?)
- exchange ("I bought this for $20", "Thanks for your help")
- replacement, to a degree (in English replacing "instead" with "for" might cause confusion)